Resistors are used for reducing voltage or limiting current flow. Chip resistor devices can generally be classified into thick film chip resistor devices and thin film chip resistor devices. The thick film chip resistor devices normally have a film thickness larger than 5 μm and are usually made by silk screen printing techniques. The thin film chip resistor devices normally have a film thickness smaller than 1 μm and are usually made by chemical vapor deposition techniques or physical vapor deposition techniques such as vacuum evaporation, magnetron sputtering, etc., in combination with photolithography.
During photolithography, a resistor layer is first formed on a substrate, followed by etching the resistor layer with the use of a patterned photoresist to obtain a chip resistor device with a desired resistor value. However, a developer used in the photolithography process is toxic and may be harmful to equipment operators and the environment. Moreover, the equipment and maintenance costs are rather high.
In an alternative method, a mask with a predetermined pattern is formed on a substrate by screen printing techniques, followed by depositing a resistor layer on the substrate. However, the mask formed by screen printing techniques tends to deform and cause an undesired resistor value shift. Furthermore, the mask must be removed by use of chemicals, which contributes to increased levels of environmental pollution.